It doesn't look like much, does it?
Does this help?
I've been wanting to try my hand at a cup sleeve/cozy/thingy for a while now, but I don't drink coffee. I didn't know what size to make it. So when visitors came bearing what they thought was garbage, I jumped with glee, washed it, and put it in the cupboard for safekeeping. I'm sure they thought I was a nutjob. Oh well.
That was a few weeks ago, but I finally made one. I discovered that it fits both sizes (don't ask me what they are, I would call them medium and large) and it fits my drinking glasses too.
It is alpaca/wool needlefelted to a foundation fabric, then fused to another piece of fabric. This should protect well from both hot and cold.